1. Field of the Invention
The present invention relates to a method for preserving pancreatic islet. In particular, it relates to a method for preserving pancreatic islet including a step of preserving a liquid containing pancreatic islet separated and purified from a living body in a container, wherein the container comprises a film having an oxygen permeation coefficient of 2500 cm3/m2·day·atm or greater. Furthermore, the present invention also covers a container for preserving pancreatic islet and a kit for transplanting pancreatic islet.
This application claims priority to JP patent application No. 2006-186105 filed Jul. 5, 2006.
2. Related Background of the Invention
Diabetes is disease caused by the disorder of action for controlling blood sugar in functions of the pancreas, and includes mainly two types, type I diabetes and type II diabetes. The type I diabetes appears at relatively early ages, and induces a symptom of strong invasion of insulin-producing cells due to autoimmune response, while the type II diabetes appears at middle and old ages, and is caused by difficulty in utilization of insulin. In Japan, it is estimated that 5% of diabetics are of type I diabetes and the number reaches about 300,000. These diabetics control blood sugar by insulin therapy, but can not be allowed to escape from the development of such complications as nephropathy, retinopathy, neuropathy. Furthermore, there are not few cases where blood sugar can not be controlled even by insulin therapy.
As a therapy method for fundamentally solving the above-described problems, there is pancreas transplantation. However, the pancreas transplantation includes such problems as heavy burden on a patient at transplant operation, and a high carcinogenic risk because a strong immune suppressor must be administered even after the transplantation.
As a novel transplantation therapy that can replace such pancreas transplantation, in recent years, pancreatic islet (also called Langerhans islet) transplantation technique has been energetically studied. The pancreatic islet means the group of endocrine cells that are scattered in an island shape in the tissue of the pancreas and contain β-cells secreting insulin. In addition, the pancreatic islet transplantation means a transplantation therapy in which pancreatic islet is separated from the pancreas offered from a donor to prepare a dispersion liquid of the pancreatic islet, and then the dispersion liquid is percutaneously administered to a patient, and a revolutionarily novel protocol was established by University of Alberta, Edmonton, Canada (Edmonton Protocol: CURRENT HUMAN ISLET ISOLATION PROTOCOL, (Edition: JONATHAN et al., Publication: Medical Review Co., Ltd)) in 2000.
In actual conditions of the pancreatic islet transplantation in Japan, pancreatic islet was successfully transplanted from a cardiac arrest donor for the first time in Japan, in Department of Transplantation, Kyoto University, in April 2004. In the future, more clinical cases must be accumulated. Also, business organizations that participate in the health industry must cooperate with this. There are few patent applications in Japan regarding the pancreatic islet transplantation, but, for example, JP-A-05-229951 discloses an invention that uses a gelatin solution as a specific gravity liquid.
The pancreatic islet transplantation has following merits.
Since it is percutaneously administered, burden on a patient at transplant operation is light (no abdominal operation and full anesthesia are required).
Even when immunological rejection occurs, there is no need for removing graft because β-cells disappear.
A small dose of immunosuppressive agent is all that is needed in a patient after the transplantation.
Even pancreas from donors that is not applicable for pancreas transplantation such as that from donors who died from cardiac arrest or arterial sclerosis can be used.
However, about 10 to 18 hours are required from pancreatectomy from a donor to preparation of pancreatic islet for the transplantation. Thus the prepared pancreatic islet must be preserved appropriately so that the pancreatic islet does not lose the vital force. In conventional methods, the preservation has been carried out by using such polystyrene tools as a flask or petri dish for culture.
However, since many of β-cells constituting pancreatic islet are deactivated or deadened in around 24 hours after the separation and purification of pancreatic islet, it is found that there is temporal restriction from the preparation of the pancreatic islet to the completion of transplant operation. For example, there is such a case that the transplant operation can not be carried out because the patient feels not well even when the preparation of the pancreatic islet transplantation has been completed, and that β-cells may be deactivated or deadened. Polystyrene petri dishes and flasks for culture conventionally used for a preservation container have a low oxygen permeability. A large amount of air was therefore required in the container, and only a small amount of pancreatic islet suspension prepared by suspending pancreatic islet could be put in the container. For example, a 100 mm petri dish can preserve only around 5 ml of a pancreatic islet suspension. Consequently, for preserving pancreatic islet separated from one pancreas, around 100 petri dishes has had to be used with a great deal of effort. In addition, when a petri dish or flask is used, pancreatic islet may adhere to the wall surface of the container, resulting in the loss of the pancreatic islet. Furthermore, containers made of polystyrene have a lid or a screw-type removable cap and have no sealing performance, so that the pancreatic islet may be contaminated with bacteria or viruses. If β-cells are deactivated, deadened, lost, contaminated and/or influenced caused by these problems, the will of the donor can not be respected.
Furthermore, at pancreatic islet transplantation, pancreatic islet has been collected from each of petri dishes or flasks as required, and has been temporarily preserved in a bag made of vinyl chloride and carried to an operation room. Concretely, a pancreatic islet liquid is aspirated from a petri dish or flask with a commercially available pipette or syringe, and then a port of the bag is punctured with a plastic needle or the like provided with a rubber coinjection part, through which the pancreatic islet is inpoured by a syringe with a needle. However, when preserved number is large, the collection and injection into a bag have had to be repeated many times, which takes a long time and so carries risks of bacterial contamination.